usually, if they put the effort in, yes they would expect/hope you to take up even the cheapest option, that said....... there is no rule saying you have to, and no specific etiquette to follow (that i know of) only things i would say are, that after putting the effort in cc swipes etc, on reaching under if the little fella isn't having any of it she should have taken the hint and probably not offered, likewise, had you stopped her sticking a finger up your ass, she would also have probably gotten the message, also given that that is hardly a staple in a standard no "thrills" massage, you probably shouldn't have let her do that if you had no intentions at that point of taking any extras (some places will class that as an extra, or part of one!)